Current production strap feed assemblies include a drive wheel and idler wheels that are operated during a four cycle banding process. The cycles include a feed cycle wherein an electric drive motor is driven in a first direction to feed a strap through a track and around the item to be banded. The drive motor rotates a knurled drive wheel with respect to an idler wheel assembly that cooperates with the drive wheel to apply drive force during the feed and tension cycles. The drive motor is controlled to rotate in an opposite direction during a tension cycle wherein the strap is pulled in a direction opposite to the feed direction outwardly of the track and around the item to cause to tighten the strap around the item to be banded.
During the tension cycle, a greater drive force is applied on the strap by the idler wheel and drive wheel during the tension cycle. Once the tensioning is complete, leading and trailing strap portions are fastened together during a crimping cycle to create a sealed connection around the item to be banded. The strap is then severed during a cutting cycle to separate a sealed strap loop from the trailing portion of the strap material.
The control assemblies for controlling the motor operating the drive wheel, command motor operation to a single forward speed until a predetermined length is fed as measured by a detector at which point the drive wheel is stopped, the free end of the strap is gripped, and the drive wheel is reversed at a single reverse speed until an external tension cut off switch is actuated.
Current strap feed control assemblies include that shown in U.S. Pat. No. 3,946,921, issued Mar. 30, 1976 in the name of Noguchi. Such an assembly discloses a feed strap control assembly which operates the strap in the forward direction for a predetermined length, and then in a reverse direction for tension. The termination of tensioning is detected by stoppage of the floating roller and/or feed roller, or speed decrease of the motor.
Other banding control assemblies utilize mechanical clutches and/or simple electric limit switches and/or valves to control feed typically air, hydraulic, or simple electric motors. These are limited to running at a fixed speed, feeding a fixed amount of strap, and tensioning to a fixed value.